Dishwashers are used in many single-family and multi-family residential applications to clean dishes, silverware, cutlery, cups, glasses, pots, pans, etc. (collectively referred to herein as “utensils”). Many dishwashers rely primarily on rotatable spray arms that are disposed at the bottom and/or top of a tub and/or are mounted to a rack that holds utensils. A spray arm is coupled to a source of wash fluid and includes multiple apertures for spraying wash fluid onto utensils, and generally rotates about a central hub such that each aperture follows a circular path throughout the rotation of the spray arm. The apertures may also be angled such that force of the wash fluid exiting the spray arm causes the spray arm to rotate about the central hub.
While traditional spray arm systems are simple and mostly effective, they have the short coming of that they must spread the wash fluid over all areas equally to achieve a satisfactory result. In doing so resources such as time, energy and water are generally wasted because wash fluid cannot be focused precisely where it is needed. Moreover, because spray arms follow a generally circular path, the corners of a tub may not be covered as thoroughly, leading to lower cleaning performance for utensils located in the corners of a rack. In addition, in some instances the spray jets of a spray arm may be directed to the sides of a wash tub during at least portions of the rotation, leading to unneeded noise during a wash cycle.